Patent Document 1 describes a conventional technology for realizing a high-speed reproduction in accordance with the content of moving picture image data. In this technology, a reproduction speed is controlled for each frame, based on a picture image feature amount associated with the moving picture image data to be reproduced for each frame.
In the following description, an amount of change in picture image between a frame i−1 and a frame i shown in the following Formula 1 (magnitude in difference between frames) is used as a picture image feature amount xi with respect to the frame i.
                              x          i                =                              ∑                          v              =              0                                      v              <              H                                ⁢                                          ⁢                                    ∑                              u                =                0                                            u                <                W                                      ⁢                                                  ⁢                                                                                              p                    i                                    ⁡                                      (                                          u                      ,                      v                                        )                                                  -                                                      p                                          i                      -                      1                                                        ⁡                                      (                                          u                      ,                      v                                        )                                                                                                                        Formula        ⁢                                  ⁢        1            
In the above Formula 1, pi (u, v) represents a pixel value of the coordinates (u, v) of the frame i, W represents a frame width, and H represents a frame height.
The flow of a reproduction operation in accordance with the above technology will be described hereafter with reference to a flowchart diagram shown in FIG. 12. First, the picture image feature amount xi with respect to the frame i is compared with a predetermined threshold value TH1 (step S001). If xi≦TH1, the reproduction speed si of the frame i is set to be si=S1 (step S002). On the other hand, if xi>TH1, the reproduction speed si of the frame i is set to be si=S2 (step S003).
Note that the relationship between S1 and S2 is S1>S2.
Next, the frame i is reproduced in accordance with the determined reproduction speed si (step S004), and each of the above steps S001 to S004 is repeated with respect to all the frames (step S005). In this way, a high-speed reproduction processing is enabled.
As described above, in accordance with the technology described in Patent Document 1, a reproduction is carried out at a high speed when a picture image change amount between frames is small, and a reproduction is carried out at a low speed when a picture image change amount between frames is large, so as to realize a high-speed reproduction in accordance with the change of the picture image feature amount in the moving picture image data.    Patent Document 1: JP Patent Publication (Kokai) No. 8-298646 A (1996)